Laminate system for a durable controlled modulus flexible membrane

ABSTRACT

A fabric system for producing at least a woven fabric of controlled modulus or elongation in the MD or warp axis, has a core layer which is the main structural element, and may have one or more woven cover fabrics adhesively bonded with an off axis configuration to one or both sides of the core layer. In a preferred embodiment the core fabric is covered with at least one off axis fabric on both sides. The cover fabrics may also have resin or film top layers laminated or coated on their outside surfaces, for mechanical performance or UV protection or both.

This application is a continuation of pending U.S. application Ser. No.10/293,828 filed Nov. 13, 2002 which claims the benefit of U.S.Provisional Application No. 60/337,732 filed Nov. 13, 2001.

FIELD OF INVENTION

This invention relates to the construction of multi-layered, controlledmodulus, special purpose fabrics, and in particular to woven fabrics ofcontrolled modulus or elongation in the machine direction (MD) or warpaxis, with covering layers bonded thereto in off axis configurations.

BACKGROUND OF THE INVENTION

The applications for flexible membranes in general include products suchas sails, airfoil and wing systems, aircraft control surfaces,inflatable structures, airships, temporary shelters, liquid storagetanks, fuel tanks, flotation devices, seals and gaskets for aircraftsurfaces, and door seals. Current materials in flexible membranes arebased on the following techniques:

Core structural fiberous components are made of bonded scrim fibergroups. These core layers of flexible membrane designs are generallyconstructed with less than 10 yarns per inch in each of two orthogonalorientations. The structure of the core layer is generally formed byresin-bonded intersections between cross machine (CM) and machinedirection (MD) yarns.

The MD and CM fibers provide along their thread lines or yarn directionsthe basic mechanical properties of elongation resistance and tensilestrength. The control of elongation is important as this property allowsthe fabrication of structures that retain their designed shape over arange of loads. The modulus of a membrane material can be approximatedby the elongation of fibers of that material under defined loads.Testing methods for measuring elongation follow ASTM (American Societyfor Testing and Materials) standards and use sample lengths up to 16inches for testing accuracy.

These scrims are not generally of woven construction, and have verylittle structural integrity when the resin bonds have been broken. Inshort this type of bonded scrim has little durability with outmodification and the addition of other components. In most systems thesescrims deliver most of the fiber content necessary in CM and MD tocontrol elongation and provide adequate tensile strength.

Fibers such as KEVLAR(™) brand para-aramid, SPECTRA(™) brand UHMWpolyethylene, DYNEEMA(™) brand UHMW polyethylene, Carbon, VECTRAN(™)brand multifilament liquid crystal polymer, Zylon(®) polybenzoxazole(PBO), TECHNORA(™) brand para-aramid, Polyester(Polyethyleneterephthalate) PEN (Polyethylene Naphthalate), TWARON(™)brand para-aramid polymer, and Nylon polyamide fiber and polyester areall used in these core element scrims. (The applicant makes no claim tothe trademarks.) Because of cost, larger yarn sizes are preferred. Mostof these scrims use structural yarns of 1000 denier or larger. In somecases smaller non-structural yarns will be used in the opposingdirection to provide for the bonding sites.

Polyester, PEN, Nylon, VECTRA(™) brand polyester film, and other filmsare used for web stability. Because the scrim core layer does notprovide off thread line stiffness, additional elements are used incurrent systems. In all current designs at least one layer of a stifffilm (e.g. ½ mil polyester) is incorporated in the laminate. The filmmost commonly used is polyester, with a film thickness of from onequarter to one and two thousands of an inch. It should be noted that theaddition of these films is not a means of adding a thermoplasticadhesive to the structure. These films are used to provideoff-threadline mechanical properties and general mechanical durability.

All or most of the interconnect between MD and CD fibers in the coreelement or layer is adhesive or resin based. Because the core elementsare not generally woven the integrity of these systems is based on thevarious resin adhesive bonds in the assembly. These resin adhesivesystems are typically crosslinked elastomers or other crosslinkedadhesive resins. Yarn is bonded to yarn and yarn is bonded to film. Theresult of this dependence on film interlayer and adhesive is that thesestructures have overall durability that is limited to the properties ofthe film and the adhesives used. The low to no twist yarn used in thesescrims contributes to these adhesive failures.

Because of the limitations of film mechanical properties, off axis fibercomponents have been developed. Some products add low count, less than15 ends per inch (epi) structures or elements on thread lines that areoff or non-aligned with the 0 to 90 degree angle between the MD and CMaxis. As with the MD and CM scrims these yarn layers are coarse, low-endcount structures. Again, like the core scrims, the off axis scrims arenot woven and at most contain crossing points only in one direction.Also like the core scrims these off axis scrims comprise yarns of littleor no twist. Twist is a secondary process and adds cost.

Because of the limitations of the non-woven core, film and off axiselements, some systems include woven cover fabrics bonded to the outsideof the system. These wovens may contain all the yarn types of the coreelements. However most cover fabrics use deniers much smaller than 1000.In all current products the cover fabric is bonded to the core materialswith its MD and CM at 0 and 90 degrees to the core elements. Only laidor bonded scrims are placed off axis.

Simple coated and saturated fabrics are also used for flexible membraneapplications. In these designs there are no scrim elements. Howeverfilms may be attached by adhesive bonding.

Resin bonded membrane systems have a catastrophic failure mode. Becausethere is little woven interlock in the structural fiber elements of thecurrent systems, the structure can fail without failure of the fiber.Low and no twist fiber contributes to this result. These structures candelaminate and the fiber separate without breakage of fiber. In flex andtear mode the potential performance of the fiber is not realized unlessthe adhesive bonding quality is equal to the fiber strength. In practicethis is not possible, so adhesive bonding failures are a cause forpremature and catastrophic failures.

Resin and films have limited properties relative to fiber. Because ofthe high dependence on resin bonding, current products are limited indurability to the flex and adhesion of the bonding mechanisms.

The cosmetics of these products may suffer from local delaminating andmildew prior to a failure in performance. Because the core and off axisfiber layers use larger yarns, there tend to be void spaces orinterstices in the fabric composite. When moisture enters these voidspaces between the films, delaminating and mildew are frequently theresult.

SUMMARY OF THE INVENTION

The applications for high strength, low stretch, flexible membranes ingeneral include products such as sails, airfoil and wing systems,aircraft control surfaces, inflatable structures, airships, temporaryshelters, liquid storage tanks, fuel tanks, flotation devices, seals andgaskets for aircraft surfaces, and door seals. There are a number ofother and emerging products that have similar high strength, lowstretch, flexible membrane performance requirements as the productslisted above. The invention is directed to a flexible membrane systemand materials that can be applied to all of these products and otherproducts having similar membrane performance requirements. The inventionis susceptible of many forms and applications.

The invention, simply stated, is a fabric or flexible membrane systemfor producing at least a woven fabric of controlled modulus orelongation in the MD or in the warp axis. This is the main structuralelement or core layer of the membrane and a principal component ofinvention. One or more woven cover fabrics may be adhesively and orthermoplasticly bonded to one or both sides of the core layer off theprimary axis, adding one or more further threadline directions ofcontrolled modulus or elongation to the system.

It is therefore an object of the invention to provide a flexiblemembrane system with a woven fabric core and woven cover fabrics allincorporating high strength fibers and a large percentage of crossingpoints, where the cover fabrics are applied with a calculated off-biasorientation to the core layer such that there is a reduced, uniformangle of shear dependence as between interlayer thread lines.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a three part diagrammatic illustration of a three layercomposite membrane with a FIG. 1A core scrim with zero angle machinedirection, to which a FIG. 1B plus 60 degree off axis cover fabric isapplied to one side, and a FIG. 1C minus 60 off axis cover fabric isapplied to the other side.

FIG. 2 is a diagrammatic illustration of a point in a composite of theFIG. 1 layers where crossings are superimposed to show the uniformdistribution and angular spacing of the machine direction and crossmachine threadlines of the three layers.

FIG. 3 is a diagrammatic illustration of a 5 layer composite membranewith a core layer and 4 off bias layers configured to provide uniformdistribution and angular spacing of the machine direction and crossmachine threadlines of the five layers.

DESCRIPTION OF PREFERRED EMBODIMENT

The invention is susceptible of many embodiments. Herein described arepreferred embodiments not limiting of the scope of the invention. In afirst preferred embodiment there is a core fabric covered with an offaxis cover fabric on both sides. It is preferred that a known chemicaladhesion promoter such as isocyanate or epoxy materials be used on theinterface of the core and cover fiber bundles. The cover fabrics mayalso have resin or film top layers laminated or coated on their outsidesurfaces. These layers may provide mechanical performance or UVprotection or both.

The core fabric is constructed in the form of a woven material using astructural fiber. The fiber may be any of polyaromatic amide,polyethylene, Carbon, multifilament liquid crystal polymer, PBO,para-aramid, Polyester, PEN, aramid polymer, and Nylon or polyamidefiber, and commercial or brand name variants thereof.

Crimp is measured by marking a length of fiber in a weave, then removingthis fiber from the weave and applying a one tenth gram load per denier.The stretched length of the fiber over the length of the fiber asmeasured in the weave is the crimp. The design of the weaving patternaffects weave crimp and fabric tear strength and damage tolerance. Theelongation under load in the thread line directions of the core elementis the result of control of crimp and the elongation characteristics ofthe yarns selected.

The design of the core material or fabric should address control of theweaving crimp in the fiber. In order to be a true weave there must becrossing points present in both axes of the fabric or core element.Unlike a bonded scrim, which has crossing points only in the CMdirection and hence no crossing point pairs a plain weave utilizes 100%of the potential crossing points. The reduction of crossing points inthe weave tends to reduce the crimp, and hence elongation. However,enough crossing points must be maintained in the weave of the corestructure to provide sufficient toughness. Core layers of preferredembodiments contain at least 5% of available cross over in the weave.The resistance of the system to abrasion and flogging will be improvedby higher levels of crossing points.

The core woven of the preferred embodiment also incorporates highmodulus yarn. There is no preferred embodiment for the fiber content ofthe core woven. There are a wide range of user mechanical andperformance requirements affecting the final selection of fiber content.The core layer or woven may contain at least one high modulus yarn ofgreater than 10 grams per denier (gpd) in warp. The core woven maycontain at least one high modulus yarn greater than 10 gpd in filling.The core woven may contain additional yarns that are greater than 10 gpdin warp or fill. Further, the core woven may contain only yarns that aregreater than 10 gpd in warp and fill.

The elongation under load in the thread line directions of the coverfabrics is the result of control of crimp and the elongationcharacteristics of the yarns selected. Cover fabric will typicallycontain more crossing points than the core structure. Issues of abrasionand damage tolerance are paramount to control of elongation in thesecover fabric elements or components of the membrane system. Thepreferred embodiment cover fabrics have warp and fill ends counts thatare greater than 15 ends per inch. End counts of 50 ends per inch inwarp and fill are more preferred in order to deliver a stable, moreeasily processed web. The higher end count also produces a fabric asopposed to an open weave scrim, which is thicker for a given amount offiber weight.

In the preferred embodiment the uncoated cover fabric has airpermeability as measured by ASTM (American Society for Testing andMaterials) methods, greater than 100 cfm/ft2 and less than 1000 cfm/ft2.This provides for a maximum level of stability while preserving adequateopen area for mechanical strike through or penetration of top coatingsto adhesives on the core layers.

Cover fabrics in the prior art can be woven of fiber that is greaterthan 1600 denier. The preferred embodiment cover fabrics of theinvention are made from fiber that is greater than 50 denier andgenerally much less than 1600 denier. These smaller yarns give the bestthickness and cover for a given mass content of fiber. Preferredembodiment cover fabrics utilize at least 5% of the available crossoversin the weave. As in the design of the core woven, the cover fabric(s)are preferably true woven with crossing points in both directions. Coverfabrics containing 100% of the crossing points are preferred forstability. The use of plain weaves gives the most stable weave possible.

Preferred embodiment cover fabrics are supplied and used as off-axiswebs in the construction of a flexible membrane of the invention. An offaxis web of cover fabric is typically formed by bias cutting from wovenor knit tubes. In this process the cover fabric is first formed as atube. The tube is then slit in a helical manner, resulting in a longsheet or off axis web of cover fabric. This process is typical of biasbinding materials. [00311 Forming of off axis web cover fabrics by biascutting and splicing allows wovens to be used that are not made onshuttle weaving machines. The thinner materials that can be made on thistype of shuttle-less machinery allow for having spliced joints in thecover fabric web which do not create large variations in the thicknessof the web. It will be readily apparent from this description that theangle of the helical cut will determine the angle of bias of the MDthreadline off the axis of the web. For example, a tube cut lengthwise,parallel to the tube axis, will result in a web with an on-axis MDthreadline, the length of the tube and the width of the tube diameter. Atube helically cut at a 45 degree angle off the tube axis will produce aweb with the MD threadline oriented 45 degrees away from the resultingedge or axis of the tube or resulting web.

After bias cutting, the cover fabrics are laminated to the core fabricwith their thread lines oriented at the angle determined by the tubebias cut angle. The tube bias cut angle, as will be readily understoodby those skilled in the art from the above description, is selected inadvance to produce the desired variation in the cover fabric bias fromthe reference angles of 0 and 90 degrees of the MD and CM thread linesof the core structure or layer.

For the purpose understanding the following examples and the claims, itcan be assumed that the MD (machine direction) and the CM (crossmachine) threadlines of the core fabric and the cover layers areconstructed at right angles. If the MD of a core layer is designated asa 0 degree reference angle, the CM of the core layer can be understoodto be at a nominal 90 degrees to the MD reference angle reference, forall practical purposes. With respect to a core layer MD threadline andthe MD threadline of a cover layer, clockwise rotation in the plane ofthe fabric or the membrane is considered positive, and counterclockwiserotation is negative, as viewed from a common side of the plane of themembrane. If the MD of the core fabric or layer is defined as the 0degree reference angle, a bias angle of a cover fabric can be stated asbetween 0 and 90 degrees positive or negative from the MD or referenceangle of the core fabric It will be understood that the bias angleapplies to the MD of the cover fabric with respect to the MD of the corefabric, and the CM's of the respective layers are displaced 90 degreesfrom their respective MDs. The distinction between positive and negativebias angles is most noteworthy when there is more than one cover layer,as will be apparent in the examples that follow.

A first preferred embodiment flexible membrane has at least one coverfabric bonded to the core fabric with its MD displaced at a 45 degreebias angle from the MD of the core fabric, so that the flexible membranesystem has four threadline angles uniformly distributed at 45 degreeapart throughout the membrane. In this example, the angular order of thethreadlines is MD_(core), MD_(cover), CM_(core), CM_(cover). Theseadditional threadlines avoid the requirement to use film to support offaxis loads.

It will be readily apparent that each additional cover layer within theoverall membrane system will add 2 more threadlines to the total,permitting a further reduction on the the average angular displacementas between all threadlines in the plane of the membrane, and permittingfurther refinement to the inter-layer orientations to optimize thedesired combination of performance parameters.

Referring to FIGS. 1 and 2, for example, in a second preferredembodiment of the invention, two covers 20 and 30 may be applied to thecore fabric 10 in various arrangements such as applying one cover to oneside of the core fabric, and one cover to the other side of the corefabric, or both both covers to one side of the core fabric. The MD linesare shown as solid lines. The CM threadlines are shown as dashed lines.No inference as to relative density, crossing point coverage or otherweave details is intended in these figures. The orientation betweenlayers 10, 20, and 30 with respect to their threadlines may be asfollows; e.g. the first cover fabric 20 can have off-axis bias of its MDangle of +60 degrees to the core fabric 10 MD reference angle, and thesecond cover fabric 30 can have an off-axis bias of −60 degrees. As willbe readily apparent from this teaching, the dashed CM threadlines of thecover fabrics 20 and 30 are oriented at minus 30 and plus 30 of the corelayer 10 MD reference angle.

Referring specifically to FIG. 2, where a crossing point in each of thethree layers of FIG. 1 is hypothetically aligned to illustrate theangular order and displacement of the threadlines, the net result of thecalculated off-axis bias in the covers is a three layer, 2 threadlinesper layer, flexible laminate or membrane or system that has afiber-based reinforcement threadline every 30 degrees in the plane ofthe membrane, with the threadlines alternating between an MD and a CMthreadline. The smaller the angle between the thread lines, the smallerthe shear angle that the matrix must support. The smaller angles and thealternating MD and CD threadlines also offer the highest control ofelongation in a nearly isotropic manner.

As another example, in a third preferred embodiment of the invention,three covers may be applied to the core fabric in various arrangementssuch as applying one cover to one side of the core fabric, and twocovers to the other side of the core fabric, their respective threadlineangles may be aligned as follows; e.g. the first cover fabric can havean off-axis bias of +45 or −45 degrees, and the other two can have anycombination of 22.5 and 67.5 degree bias angles, both being eitherpositive or negative angles from the reference angle of the core layer.This provides a membrance system that has fiber-based reinforcementevery 22.5 degrees in the plane of the membrane. The smaller the anglebetween the thread lines, the smaller the shear angle that the matrixmust support. The orientation of MD's to CD's in the plane of themembrane is not ideally distributed in an alternating manner when thereis an odd number of covers and each is used with an exclusive biasangle, but the smaller angles still offer the highest control ofelongation in a nearly isotropic manner.

Referring to FIG. 3, more covers can be integrated into the design usingthe principles of the invention to select bias angles contributing tothe omnidirectional performance of the membrane. Here, illustratedsimilarly to the example of FIG. 2, four off-axis covers 41, 42, 43, 44have been added to a core layer 40, with bias angles of plus and minus36 degrees and plus and minus 72 degrees, resulting in an MD-CM-MD-CMalternating order of threadlines at 18 degrees apart.

It will be apparent from the above description and examples, and iswithin the scope of the claims, that in the alternative, while notpreferred, the core fabric can be produced and prepared for assembly ofthe membrane as an off-axis web. The actual MD, although off axis fromthe running direction of the roll or web from which it is dispensed, maystill be designated as the reference angle of the core layer. The MD andCM threadline angles of cover layers are still appropriately referencedand calculated from the actual MD threadlines of the core fabric web,even thought it is not aligned with the length or running direction ofthe core layer roll or web.

There is no preferred embodiment for yarn type and total fiber contentin the cover fabrics. Like the main structural layer, various grades ofthe system are useful. Depending on the range of modulus and tensileproperties required for a specific application, the fiber type andcontent can be adjusted. For example, the cover fabric may contain yarnof greater than 10 gpd. The cover fabric may contain yarn of less than10 gpd. And the cover fabric may contain yarn of greater than 10 gpd andyarn of less than 10 gpd.

Lamination systems for bonding core and cover materials provide highpeel and tear strength. Core materials or fabrics of the invention, bytheir design, have controlled and limited void content left unfilled byresin after the cover fabrics are applied and the lamination process iscomplete. This limited void content reduces the potential fordelaminating and mildew problems. In a preferred embodiment membrane,resin is in intimate contact with the core fibers and the cover fibers.Its preferred that a chemical bonding agent be used at this fiberinterface to inprove adhesion. There are no film layers between thefirst fabric cover and the core fabric. Without the use of structuralfilm layers, the adhesive resin systems surround and penetrate the wovenelements. This allows for the preferred combination of chemical andmechanical bonding.

The elimination of the film between the cover fabrics and the corefabric permits the cover fabric to be fully saturated with the adhesiveresin without significant levels of voids between it and the core layer.The preferred embodiment lamination method and resulting laminate ofcore and cover does not require film for mechanical performance, but itmay contain a film layer at some level external of the structuralcombination of core and cover for further purposes such as UVresistance.

Thermo plastic resins and coating can be used for thermal repair andheat-sealing for joining of seams when assembling webs of the membraneinto useful structural forms such as fluid airfoils, diaphragms,envelopes, and partitions.

Top coating or film can provide good levels of UV (ultraviolet light)protection to the fiber. The materials that provide good UV protectionare well known to those skilled in the art. The selection will depend onfactors including cost, weight, total life, heat-sealing, and adhesionto other layers. Materials that provide UV protection include but arenot limited to EPDM (Ethylene Propylene), Hytril (EBXL-Hytrilthermoplastic elastomer), Hypalon(®) brand chlorosulfonated polyethyleneelastomers (CSPE), silicone, florosicones, Aliphatic urethanes, acrylicfilm, floro polymers like Tedlar(®), Kynar(®) or Teflon(®) brandproducts, vinyl films, and other materials know for their UV resistance.(No claim is made to any such terms as may be trademarks.) Topcoats orfilms can provide pigmentation and coloration for UV and aestheticreasons. The addition of pigments to coatings is also well known tothose skilled in the art.

In the case where a different fluid is present on the backside of themembrane system, select fibers, yarns, and fabrics, and in particular,special coatings and films appropriate to the particular fluid many beused. The materials may be selected to provide different or additionalfeatures or improvements such as solvent resistance, chemicalresistance, and controlled permeability to gases.

There are a large number of coatings and films and their severalapplications that are well known to those skilled in art and are equallyapplicable here. Given the large number of potential materials that canbe contained in the membrane system of the invention, it is not possibleto list all possible combinations. Most of the UV resistant materialslisted above have applications to the fluid and gas retention. A fewmaterials are unique to gas retention, such as Polyester films, butylrubber, and Aclar films.

A preferred embodiment flexible membrane of the invention, suitable foruse as an airfoil for a large offshore yacht, for example, utilizes acore material which contains 1500 denier Vectran HS(®) brandmultifilament liquid crystal polymer yarn in the MD. The construction is30 yarns in the MD. In this example the stretch or modulus in the MD isless than ¼ percent at a 10 lbf/inch, (pounds force per square inch)with a breaking load of 1690 lbf/inch.

In the cross machine direction the yarn is 1500 denier Vectran HS(®)type thermoplastic material and 500 denier polyester. The weave is 6ends of polyester and one of the thermoplastic material, repeated threetime per inch, for a total of 21 epi. In this example the stretch of theCM is ½ percent at 10 lbf/inch, with a breaking load of 230 lbf/inch.

The weave pattern is modified basket 2×2×2×1 in the fill with thepolyester weaving as a pair and the thermoplastic material weavingsingle. The polyester yarn does not provide the high modulus behavior inthe filling but the additional crossing points add significantly to theoverall mechanical properties of the woven. The total crossing points ofthis example is 78%.

The cover fabric for this embodiment is made of a polyester yarn of 70denier. The weave construction is 50×50 epi. The uncoated permeabilityas measured by ASTM methods is 400 cfm/ft². The weave is plain.

The cover fabric is scoured free of contaminants and coated withstabilizing adhesive resin such as a urethane. The resin coating helpsstabilize the cover fabric during the biasing process. The cover fabricis cut and formed into a 45-degree bias materials as described above,using adhesive bonding of lap joints where necessary.

The core material is coated both sides with a urethane resin and abiased cover fabric is applied to each side in a lamination process.

A top coating is made of a resin based on aliphatic urethane, pigmentedwith five percent by weight of titanium dioxide pigment. The coating isapplied to the each of the cover fabric in a 1.5 mil thickness. The massper square yard of the laminate is 17.5 oz/yd². The thickness of thecoating is 22 mils. The resulting flexible membrane system as tested bythe applicant had an MD slit tear measurement when performed to FAA(Federal Aviation Administration) standards, of 580 lbf/in.

As will be readily understood by those skilled in the art, the preferredembodiments are illustrative of the invention, and not exhaustive of thescope of the invention. Other and various embodiments are within thescope of the invention as described above and claimed below.

For example, there is within the scope of the invention a flexiblelaminate system with at least one core consisting of a fibrous layerconfigured with elongation in the MD at 50 pounds force per inch of webof less than 0.5 percent elongation, and at least one cover comprising afabric layer with yarn spacing in at least one direction greater than 15ends per inch, where the cover is bonded to the core with the cover MDaxis at a bias angle with respect to the core MD.

The bias angles may be about 45 degrees respectively. The cover may beat least a first and a second cover, where the first cover bias angle isabout +60 degrees, and the second cover bias angle is about −60 degrees.And the at least one cover may be at least a first, second and thirdcover, where the first cover bias angle is about +22.5 degrees, thesecond cover bias angle is about −45 degrees, and the third bias angleis about +67.5 degrees. And also, the at least one cover may be at leastfirst, second, third, and fourth covers, where the covers haverespective bias angles of about +36 degrees, −36 degrees, +72 degrees,and −72 degrees.

Also, the at least one cover may be multiple covers, where the coversare bonded to the core with respective cover MD's at different biasangles with respect to the core MD. The fibrous layer may be a wovenlayer having less than 2 percent crimp in the MD. And the woven layermay have less than 50% of its available crossing points. The flexiblelaminate system may further consist of a UV protective film layerexternal of the core and the cover.

As another example, there is a flexible laminate system with first andsecond woven layers, where the first layer has less than 2% crimp in theMD, and the second layer includes at least one cover layer with yarnspacing in at least one direction of greater than 15 ends per inch. Thefirst woven layer is combined with the second woven layer such that thefirst layer is bonded to the cover layer with the cover layer MD at abias angle to the first layer MD. Also, the second woven layer mayconsist of multiple cover layers, where the first layer is combined withthe second layer such that the cover layers are bonded to the firstlayer with respective cover layer MDs at different bias angles withrespect to the first layer MD.

The first woven layer may have elongation in the MD at 50 pounds forceper inch of web of less than 0.5 percent. The first woven layer may haveless than 50% of its available crossing points used.

As yet another example, there is a flexible laminate system with firstand second woven layers, where the first layer is a core layer that hasless than 50% of its available crossing points, the second layerconsists of a cover layer with yarn spacing in at least one direction ofgreater than 15 ends per inch, and the cover layer is bonded to thefirst layer with its cover layer MD at a bias angle to the first layerMD. Also, the second woven layer may be or have multiple cover layers,where the first layer is combined with the second layer wherein thecover layers are bonded to the first layer with respective cover layerMDs at different bias angles with respect to the first layer MD.

The first woven layer may have elongation in the MD at 50 pounds forceper inch of web of less than 0.5 percent. The first woven layer may haveless than 2% crimp in the MD.

There is also another example; a flexible laminate system consisting ofa core and at least two covers of a common cover fabric, where the coreuses 1500 denier thermoplastic multifilament liquid crystal polymeryarn, the core construction has up to 30 epi in the MD with elongationin the MD of less than 0.25 percent at 10 lbf/inch. The core consists ofmutlifilament liquid crystal polymer yarn and polyster yarn alternatedin a modified weave pattern having at least 21 epi in the CM, withelongation in the CM of not more than 0.5 percent at 10 lbf/inch. Thetotal core crossing points consist of greater than 50 percent. Thecommon cover fabric consists of 70 denier polyester yarn woven at 50×50epi, with a resin coating, cut and formed with a 45 degree bias angle.There is a cover applied to one or each side of the core, and analiphatic urethane resin top coating is applied to each cover.

Other examples within the scope of the invention and the claims thatfollow will be readily apparent to those skilled in the art from thedescription and figures provided.

1. A flexible laminate system with angularly distributed, controlledmodulus threadlines comprising: a flexible core layer with yarn spacingof greater than 15 epi and up to 30 epi in the MD, and having anelongation in the MD of less than 0.25 percent at 10 lbf/inch and lessthan 0.5 percent at 50 lbf/inch; and at least one fabric cover layeroriented with its respective threadlines at a bias angle with respect tothe threadlines of said core layer, said cover layer being bonded tosaid core layer and having a resin top coating applied thereto.
 2. Theflexible laminate system of claim 1, said at least one fabric coverlayer comprising at least two said fabric cover layers.
 3. The flexiblelaminate system of claim 1, said core layer having less than two percentcrimp in the MD.
 4. The flexible laminate system of claim 3, said corelayer having at least 21 epi in the CM and an elongation in the CM ofnot more than 0.5 percent at 10 lbf/inch.
 5. The flexible laminatesystem of claim 4, said core layer comprising fibers from among thegroup of fibers consisting of polyaromatic amide, polyethylene, Carbon,multifilament liquid crystal polymer, PBO, para-aramid, Polyester, PEN,aramid polymer, and Nylon or polyamide fiber.
 6. The flexible laminatesystem of claim 5, comprising a uniform angular distribution of themachine direction and cross machine threadlines of said core and coverlayers.
 7. The flexible laminate system of claim 6, said cover layershaving an uncoated air permeability of greater than 100 cfm/ft2 and lessthan 1000 cfm/ft2.
 8. The flexible laminate system of claim 7, said corelayer comprising thermoplastic multifilament liquid crystal polymeryarn.
 9. The flexible laminate system of claim 7, said core layercomprising 1500 denier thermoplastic multifilament liquid crystalpolymer yarn.
 10. The flexible laminate system of claim 7, said coverlayer comprising polyester yarn configured at greater than 15×15 epi.11. The flexible laminate system of claim 7, said cover layer comprising70 denier polyester yarn configured at 50×50 epi.
 12. The flexiblelaminate system of claim 7, an aliphatic urethane resin top coatingapplied to at least one said said cover layer.
 13. The flexible laminatesystem of claim 10, said core layer comprising thermoplasticmutlifilament liquid crystal polymer yarn and polyester yarn alternatedin a modified weave pattern.
 14. The flexible laminate system of claim7, further comprising defined inner and outer surfaces, and having atleast one film top layer on the outer surface.
 15. The flexible laminatesystem of claim 7, comprising a core layer weave density of less than50%.
 16. A flexible laminate system with angularly distributed,controlled modulus threadlines comprising: a flexible core layer withyarn spacing up to 30 epi in the MD, elongation in the MD of less than0.25 percent at 10 lbf/inch and less than 0.5 percent at 50 lbf/inch,and yarn spacing of at least 15 epi in the CM and elongation in the CMof not more than 0.5 percent at 10 lbf/inch, said core layer comprisingfibers from among the group of fibers consisting of polyaromatic amide,polyethylene, Carbon, multifilament liquid crystal polymer, PBO,para-aramid, Polyester, PEN, aramid polymer, and Nylon or polyamidefiber; and at least two fabric cover layers comprising polyester yarnand oriented to said core layer with their respective threadlines at abias angle with respect to the threadlines of said core layer, saidcover layers being bonded to said core layer and having a resin topcoating applied thereto, said layers of said laminate system beingadhesively bonded together, said laminate system further comprisingdefined inner and outer surfaces, and having at least one film top layerbonded to said outer surface.
 17. The flexible laminate system of claim16, comprising a core layer weave density of less than 50%.
 18. Aflexible laminate system with angularly distributed, controlled modulusthreadlines comprising: a fabric core layer and at least two fabriccover layers, said core layer having less than two percent crimp in theMD and elongation in the MD of less than 0.25 percent at 10 lbf/inch,said core layer comprising thermoplastic multifilament liquid crystalpolymer yarn and polyester yarn alternated in a modified weave pattern,and having at least 21 epi in the CM, with elongation in the CM of notmore than 0.5 percent at 10 lbf/inch, said cover layers comprising awoven polyester yarn fabric of at least 50×50 epi with resin coating,cut and formed with a bias angle with respect to said core layer, a saidcover layer adhesively bonded to each side of said core layer, and analiphatic urethane resin top coating applied to each said cover layer.19. The flexible laminate system of claim 18, comprising a core layerweave density of less than 50%.
 20. The flexible laminate system ofclaim 19, comprising a core layer weave construction of at least 15 andup to 30 epi in the MD.
 21. The flexible laminate system of claim 20,said core layer having elongation of the MD at 50 lbf/inch of web ofless than 0.5 percent.